Furnace fuel control



P 7, 1953 J. o. THORSHEIM FURNACE FUEL CONTROL Filed April 5, 1948 2SHEETS SHEET l J. O. THORSHEIM FURNACE FUEL CONTROL April 7, 1953 2SHEETSSHEET 2 Filed April 5, 1948 Zmnentor JOSEPH 0. 7/10/7191A67/7 II kPatented Apr. 7, 1953 FURNACE FUEL CONTROL Joseph 0. Thorsheim,Minneapolis, Minn., as-

signor to Minneapolis-Honeywell Regulator. Company, Minneapolis, Minn.,a corporationof Delaware Application April .5, 1948, Serial No. 19,120

4 Claims. 1

This invention relates to a furnace fuel control for regulating the flowof oil to an oil burning furnace. More particularly, the invention isconcerned with a control device which provides for a low rate of fuelfiow to maintain a pilot flame inthe furnace and at least one otherlarger rate of fuel flow to provide high fire operation of the furnace.

There are numerous control devices which provide the above mentionedfurnace operation but many of themperform in an unreliable manner.Thosewhichrely on the metering of fuel through a small orifice toprovide low fire operation of the furnace, probably give the leastreliable performance, This is usually due to the gumming of the smallorifice.

One of the objects of this invention is to provide a furnace fuelcontrol which will provide an extremely low and uniform rate of. fuelflow for maintaining a pilot flame in the furnace, without having thefuel flow through a small passageor orifice.

Another object of the invention is to provide a control which uniformlyand regularly delivers a metered charge of fuel to a furnace.

A further object of the invention is to provide a control which deliversmetered charges of fuel to the furnace and which has. means for varyingthesize of the charges.

' A still. further object of the invention is to provide a control whichhas a valve associated there.- with which will cut off the flow of fuelif one or more of a plurality of undesirable conditions arise.

Another object of the invention is to provide a control having a simplemeans for manually opening a safety valve therein and to reset acondition-responsive valve-actuator therefor.

Another object of the invention is to provide a; compact controlhavingfuel metering'means and a safety valve with concealed passagesconnecting them.

Still further objects of the invention will be come apparent uponreading the following de tailed description of the invention inconjunction with the accompanying drawings wherein:

Figure 1 is an elevational view .of the control with portions thereofbroken away;

Figure 2 is a plan view of the control with its cover removed andPort-ions thereof broken away;

Figure 3 is a cross-sectional view of the safety valve of the control;

Figure 4- is a cross-sectional view of an accumulator in the control,taken on line 4-4 of Figure l;

Figure 5 is a cross-sectional view of a control valve in the control,taken along line 5-5 of Figure 1 and with parts thereof broken away andremoved;

Figure 6 is a cross-sectional View of the abovementioned control valvetaken along the bearing plane surface of the valve;

Figure 7 is a plan view of a power adjusting" means for theaccumulatorwith portions thereof broken away and the accumulator shownin cross-section;

Figure 8 is a sectional view taken on line 8-8 of Figure 1; and

Figure 9' is a sectional view taken on line 9--9 of Figure 1.

The furnace fuel control comprises a wall member, generally designatedby the reference numeral H, adapted to be secured to a furnace by anysuitable means (not shown) or to a rigid support positioned in thevicinity of the oil burning furnace. The wall consists of a thick plate12 having a plurality of grooves formed in the inner surface thereof andwhich terminate in bores extending from the bottom of said groovesthrough the plate to the outer surface thereof. The functions of thesegrooves will be described hereinafter. Another thinner plate I3 isclamped to plate 12 by means of a plurality of screws (not shown) with asheet of any suitable gasket material is tlierebetween. It is thus seenthat the grooves in the plate l2 and the gasket material l4 form thewalls of passages adapted to conduct fuel oil from one of theabove-mentioned bores to another.

Secured to the wall I l, against the outer face of plate I2 and at theright hand end thereof, as viewed in Figures 1 and 2, is a filteringunit [5. It consists of a casing 16 enclosing a wire mesh filter ii, afuel inlet tapping I8 and an outlet bore ill. The details of the filterunit form no part of this invention. It may take the form of most anyconventional filter.

Mounted on the outer surface of plate 12 adjacent the filter unit, bymeans of screws 20, is a safety shut-off'valve generally designated bythe reference number 2|. As can best be seen in Figure 3, the safetyvalve comprises a housing 22 having a cone-shaped chamber 23 at itsinner end terminating in an axial bore 24. A slot 25' extends from thelower edge of the housing 22 upwardly into the bore 24 and from theouter edge of the housing 22 inwardly to a point spaced from the chamber23. Extending. vertically through the outer portion of the housing 22and intersecting the-slot 25 is an elongated opening 26. A diaphragm 21is positioned between the housing 22 and a ring 28. All three of theseelements are secured to the plate l2, with a gasket washer 29therebetween, by means of the abovementioned screws 28. A valve 38 issecured to the center portion of the diaphragm 21 by means of a threadedstem thereon passing through an aperture in said diaphragm and intothreaded engagement with a plunger 3| slidably mounted in the bore 24.The plunger 3| has a diametrical slot 32 therein and an extension ofreduced diameter at its outer end. A spring 34 resiliently urges theplunger 3| inwardly to normally seat the valve 35 in a terminal bore ofpassage 35. The passage 35 establishes communication between the outletIQ of filter unit l5 and a chamber 38 between the diaphragm 21 of safetyvalve 2| and plate I2. The outlet from chamber 36 will be describedbelow. Pivoted in the slot 25, on pivot 31, is a bell crank lever 38having an actuating arm 39 and a power arm 40. The arm 40 extends intothe slot 32 for actuation of the plunger 3|.

Vertically slidable in opening 26 is a bar 4| having an aperture 42therein through which the outer end of arm 39 extends. Slidably mountedon the bar 4| is a manually operable latch member 43 that is best seenin Figure 1. Slots 44 and 45 therein enable the member 43 to slide overthicker washers 48 and between the heads of bolts 4'1 and 48 and the bar4|. A tension spring 49, anchored to the lower end of member 43 and thebolt 48, normally urges the member 43 upwardly with respect to bar 4| toposition the pin 41 against the lower end of slot 44. This provides alost motion connection between the members 43 and 4| for resettingpurposes. A laterally extending arm 50 on the latch member 43 has atransversely bent shoulder portion 5| and a vertical slot 52. A notch 53in the lower left hand edge of the member 43, as viewed in Figure l, isadapted to cooperate with a bell crank lever latch 56 to hold the valve30 open, the spring 49 being strongerthan the spring 34. A pivot 54extends through the upper ends of the legs of a U-shaped arm 55 of thebell crank lever and through slot 52, and is rigidly secured to plate[2. The slot 52 merely enables the latch member to move downwardly overthe pivot 54 to reset the latch as described hereinafter. The springbiased lost motion connection between the members 43 and 4| provides aresilient strain release connection between the manually operable latchmember 43 and the valve 30 through the bar 4|, lever 38 and plunger 3|,so that the latch member can continue to move after the valve has openedfully, to permit this resetting action. A spring 55a may also beprovided between the outer end of arm 55 and a fixed portion of thecontrol, to partially balance the weight of a float to be presentlydescribed. The outer end of the other arm 51 of the bell crank lever 56,is pivoted to the upper end of a stem 58 which, in turn, is secured atits lower end to a float 59.

" A trough or drain 68 has a float chamber 6| positioned substantiallycentrally thereof, a well 62 receiving the lower end of the filter unitl5. and drain surfaces 53 and 64 converging downwardly and slopingtoward the back to the top of fioatchamber 5|. The drain B8 is securedto plate I2, with a gasket or cement therebetween, by means of screws(not shown). The drain also has a threaded outlet opening 65 and a bore66 extending laterally from said opening 55 through the rear wall of thechamber 6| or drain 60 to aline with a terminal bore of a groovedpassage 56a in the plate l2. The other terminal boreof passage 65a ispositioned above chamber 6|. A bore 61 extends through the bottomportion of the side wall of the float chamber 6| to aline with aterminal bore of an inverted, U- shaped, grooved passage 57a. in platel2. This passage loops over the passage 66a and connects with outletthrough a passage 84, to be described below, and bore 66.

Positioned near the center of the control, above the drain 68 and to theleft of the valve 2|, is an accumulator generally designated by thereference numeral 68. As can best be seen in Figure 4 of the drawing,the accumulator comprises a base member 69 having a recessed portion In,a diaphragm H, a piston 12 which is biased by means of a spring 13toward the base member 69, a guide ring 12a, and an adjustable stopmember '54. The accumulator is secured to the plate l2 by means ofscrews 15 with a gasket 16 therebetween. An opening 11 through thegasket 16 establishes communication between the recess 10 of theaccumulator and a terminal bore of a passage 82 (described below) inplate l2. It is thus seen that when the adjustable stop 14 is screwedoutwardly, oil under pressure may flow into recess 18 and move thediaphragm and piston 72 outwardly into engagement with the end of stop14. When fuel pressure is relieved, the spring 13 may then force thepiston 12 and diaphragm l toward member 59 and discharge fuel oil fromrecess 10.

The means for controlling the flow of fuel oil to and from theaccumulator 58 comprises a retary control valve 18, best seen in Figure5. It has three radially extending grooves 19 communicating throughconcentrically spaced slots 88 in a sleeve-like bearing member 8| with aterminal bore of passage 82. The bearing member extends into the boreand rotates therein. The passage 82 is the one that communicates withchamber 70 of the accumulator 68. The outer endof the grooves 19 areeach adapted to successively .pass over the terminal bores of passage 83and passage 84 (see Figure 1). These terminal bores are spaced apart adistance greater than the width of the grooves 79 and are less thanapart. This assures that only one of these terminal bores can be influid flow engagement with a groove 79 at a time. The passage 83 leadsto a terminal bore communicating with chamber 36 in the safety valve 2|.The passage 84 leads to a terminal bore in alignment with bore. 66 toestablish communication with the outlet 65. A boss on the outer surfaceof the control valve 18 is slotted at 85 to receive a drive plate 86.

The drive plate 86 is driven by a flanged coupling 81 having a slot 88in a boss thereon, similar to the slot 35. A coil compression spring 89surrounds the bosses on the members 18 and 81 and the drive plate 85 tohold them in axial alignment and to urge the valve 18 away from thecouplmg 81 and into engagement with plate l2. The

7 coupling 81 has a slot in the opposite wall thereof at right angles tothe slot 85. This slot is engaged by a tongue 9| of a drive shaft 92.The drive shaft 92 is rotated at a constant speed by means of a geartrain (not shown) which in turn is driven by a synchronous motor (notshown) enclosed in the housing 93. The motor housing 93 is mounted onthe plate l2 by means of bolts 94 extending through spacing sleeves 95.The distance of the housing 93 from the plate I2 is sufficient to allowa slight amount of play of the ap ease-4;

drive -plate m6 fin the slots 95 and 88, but is sufficiently 'close soas :to keep the spring zse under enough compress'ion to maintain thev-alve T8 in oil seal'ing engagement with 1. the surface of plate l-2.lit will :be noted that the screw-threaded, adjustable abutment '14 isthreaded through a lateralprojection 93a extending fremra side "wall ofthe motor easing 93. Current is @supplied *to the'smotor throughlleads"92a.

Modification In icthe .modification of the accumulator :shown inFigure'-' 7 ,"thepiston l 'l'zrrha's azlaterally extendingtstem HZbwhichslida-bly fits .in an axial bore 96 of a plunger .91. The plungerL9] .sl-idably fits in the epentend-of an --inverted, :cup *shapedmemberH98. I,'he member 98 has a .diame-trical slottherethrough,providinga-slot-99 on one. side and a much longer slot'lllllzon -rthe otherrside. .An axial ,bore .in the closed end --of thevcup-shaped member as receives the 'unthreaded end of athreadedadjustment screw 14a whichis threaded through a fixed support931). Extending through theslots 99 and I90 is a wedge-shaped plate 194which, in operation, bears against one end each ofslots 99 and 1.011 and.the end oflplunger-sl, to limit the outward movement of the piston H2.The large end of the plate i! is connected by means of ascrew 1B2toabimetallicstrip I03. A slot .(not shown) in the bimetaliplate permitsthe passagetof thescrew 1702 and .allows for longitudinal movement ofthe screw and plate it! with respect to the bimetallic strip. This 621-ables the side .edges of the plate ill! to properly bearagainst theends.of .slots 99 and 109 and the end of plunger :91. The position of thehead of thescrew .102 with respectto the adjoining surface of thebimetallic member, permits, if desired, a slight amount vof movement ofthe .bimetallic member in one directionand then the other directionbefore the plate fl)! is moved. One-end of the bimetallic member issecured to a lateral projection 104 on the plate lza, while the centerportion of the :jbimetallic member carries a resistance heater I that isadapted to be energized through a room thermostat (not shown) by asource of electrical energy (not shown). The room th'ermostat may be ofthe 'on-off type or may be of the potentiometer type.

The first would give a two-position operation of the plate H1] while thesecond would provide a many-position operation thereof.

Operation 'The device is shown in 'its operating position in'Fig-ures1,72 and 3, that is, with the float in its lowere d'p0sition,'thesafety'valve open and the adjustable "abutment'in 'a position to permitthe diaphragm'of the accumulator to move outwardly against the bias of"spring .13 under oil supply pressure. As the synchronous motorconstantly rotates'the control "valve 78 at a uniform speed,registration of'the end of one of the grooves I?! with a terminal bore'of passage 83 will permit the flow of fuel through the filter unit l5,passage 35, valve 2|, passage 83, control valve 18, and passage 82 tothe chamber Hi of the accumulator 68. This permits the oil under itssupply pressure (gravity or pump) to force the diaphragm and the pistonagainst the abutment to accumulate or store a metered charge of the fueloil. Continued movement of the control valve will first cut offcommunication between the chamber and the oil supply and then establishcommunication between the chamber and the fuel outlet 65 leading to thefurnace. The discharge large openings.

is .-.-accomplished *by the v groove "l9 -in .ithe control valveregistering with the lterminali'borelof rp'assage 84 which leads to theoutlet :65 through bore 66. "The provision of three grooves 1:9 in thecontrol valve-causes three .accumulations ian'd discharges for eachcomplete :rotation of :the control valve.

By adjusting .the adjustable abutment or stop outwardly, the rateofifuel fiowmay be increased inasmuch as a greater' volumeaof fuel:oilwill accumulated every time the accumulator :is :put intofcommunicationiwith the source of fuelesupply. This may be done eithermanually :by :rotating theiscrewethrea'ded :abutment 1:4 in Figure 4201*automatically by the'croom thermostat causingthe energization of "theresistance heater 211135 to :cause'warpingiof the bimetalintthezdirection of the-arrow shown .inlFi'gurefl.

The control will continue to deliver fuelzata uniform rate at whateverabutment setting is provided. This will :be true even :for the .minimum.lfiow rate in that fuel 'oil does :not have to flow through asmall-metering orifice or "passage but by "periodic surges of fuelthrough relatively This prevents the clogging 0f the fuel passages and,therefore, provides trouble free r-andluniform operation of the furnace.

Figure 4 shows thezabutment T4 in its nc-tiles. position, with thepiston and diaphragmyheid against the base member as by the adjustableabutment 14. In this position no :dischargeable fuel can be accumulatedor discharged, as the piston 12 and diaphragm "H .cannotmove outwardlyunder the .oil supply pressure against the bias of spring 13.

Should the flame in the furnace become extinguished, the fuel oil willaccumulate in 'the furnace to 'only'that level which will cause th'efuel oil to back up into the discharge opening 65, through bore 156,through passage "615a and into chamber 61. This will cause the float 159to be raised to disengage latch arm 55 from the notch '53 in latchmember 4'3. As soon .as the latch -member 43 is freed, the spring 34 inthe safety valvewill move the valve 3.0- .into seating engagement withthe terminal bore of passage 35 and raise the bar 41 and the latch-member 4-3 to their elevated'positions by means rof the bell cranklever .38.

The same safety action would take placeif any one or all of the'unitsmounted on the platefl started to .leak. For example, if the diaphragm Hin the accumulatorshould :spring a leak, the oil escaping around thepiston would be caught by the upwardly' and outwardly'inclined surfaces63 and 64 which would direct the oil into vthe float chamber 61. It isthus seen that if any conditionshould arise that would possibly causethe flooding :of oil over the area of thefurn'ace installation, thesafety valve 'would'automatically be tripped by the float mechanism toshut off the flow of fuel.

To resetthe device after the'furnace has been conditioned for operation,the upper end of the latch member 43 is manually moved downwardly tofirst cause the bell crank lever 38 to open the valve 30, against thebias of spring 34, and then to slide the member with respect to the bar4|, against the tension of spring 49, to bring shoulder '5l intoengagement with arm 51, pivotally connected to the float 59 through stem58. Further downward movement forces the float to the bottom of chamber6|. As the float 59 is substantially the same diameter as chamber 6|,fuel oil will be forced outwardly through bore 61 to prime the siphonpassage 61a connected to the passage 8-4 adjacent the outlet bore 66.This will cause rapid discharge of the fuel oil from the chamber 6| tothe furnace or, if desired, to waste, if the conduit to the furnace isdisconnected. Lowering of the arm also brings the arm 55 into a verticalmovement path of the bottom edge of notch 53 so that, the releasing oflatch member 43, will not cause the lifting of bar 41 to close the valve30 but engagement of the bottom edge of the notch 53 with the bottom ofarm 55.

While the preferred embodiment of this invention has been describedabove, it is apparent that various modifications may be made thereinwithout departing from the spirit of the invention. Therefore, it is tobe understood that the scope of the invention is to be determined not bythe above specific disclosures, but by the appended claims.

I claim as my invention: 7

1. A furnace fuel control comprising a substantially vertical wallhaving inlet and outlet passages formed therein, a valve mounted on saidwall for controlling the flow of fuel through said passages, a floatchamber secured to said wall under said valve and having upwardly andoutwardly inclined drain surfaces, a fuel feeding means mounted on saidwall above said drain surfaces and connected to said inlet passage, apassage in said wall providing communication between an upper portion ofsaid chamber and a lower portion of said outlet passage, an invertedU-shaped passage in said wall providing communication between the bottomof said chamber and a lower portion of said outlet passage and havingthe bridge of said U-shaped passage above said chamber, a float ofslightly smaller diameter than said chamber pivotally connected to abell crank lever having a latch thereon, and manually operable means foropening said valve and forcing said float downwardly in said chamberwhereby fuel is forced into said U-shaped passage to prime it and causethe discharge of fuel from said chamber, said manually operable meanshaving a strain release connection with said valve and a laterallyextending arm for engaging said bell crank lever and an abutment thereonfor engaging said latch only when said float is in its lowered positionin said chamber.

2. In a control device for supplying fuel to a furnace and having avertical wall with inlet and outlet passages therein, the combinationcomprising fuel feeding means on said wall, a biased closed safety valvemounted on said wall for controlling the flow of fuel through saiddevice, latch means for actuating said valve to its open positionagainst its bias, said latch means having a resilient strain releaseconnection with said valve to permit continued movement thereof beyondthe open position of said valve, a float chamber on said wall and havingdrain surfaces extending laterally from the top thereof and beneath saidvalve and fuel feeding means, a passage in said wall between said outletand an upper portion of said chamber, an inverted generally U-shapedpassage in said wall having a short leg thereof terminating in a lowerportion of said chamber and a longer leg thereof terminating in saidoutlet at a lower level, a float of slightly smaller width than saidchamber and positioned therein, and pivoted latching means connected tosaid float and engageable with said latch means to hold said valve openwhen said float is low in said chamber and disengageable from said latchmeans when said float is high in said chamber to cause closing of saidvalve.

3. A safety float chamber for a'fuel control device comprising, achamber, an adjoining wall extending upwardly beside and beyond theupper edge of said chamber for supporting a plurality of fuel controlmeans above said chamber, an inverted generally U-shaped passage formedin said wall with the lower end of one of the legs of said passageterminating in a lower portion of said chamber and the lower end of theother leg terminating in a discharge passage of said device at a lowerlevel than the bottom of said chamber, and another passage formed insaid wall extending from said discharge passage to a portion of saidchamber.

4. A safety control device comprising, a chamber, an adjoining wallextending upwardly beside and beyond the upper edge of said chamber, aplurality of fuel controlling means mounted on said wall above saidchamber, an inverted generally U-shaped passage formed in said wall withthe lower end of one of the legs of said passage terminating in a lowerportion of said chamber and the lower end of the other leg terminatingin a discharge passage of said device at a lower level than the bottomof said chamber, and another passage formed in said wall extending fromsaid discharge passage upwardly between said legs to a top portion ofsaid chamber.

JOSEPH O. THORSHEIM.

REFERENCES CITED The following references are of record in the flle ofthis patent:

UNITED STATES PATENTS Number Name Date 915,780 Malcolm Mar. 23, 19091,144,525 Blake June 29, 1915 1,600,507 Marr Sept. 21, 1926 2,174,055Coleman Sept. 26, 1939 2,219,473 Delancey Oct. 29, 1940 2,242,582Jencick May 20, 1941 2,317,556 Russel Apr. 27, 1943 2,319,830 SampselMay 25, 1943 2,323,627 Sherman July 6, 1943 2,330,243 Sampsel Sept. 28,1943 2,333,602 Van Almelo Nov. 2, 1943 2,349,209 Taylor May 16, 19442,355,870 Johnson Aug. 15, 1944 2,367,545 Udale Jan. 16, 1945

